CN117457910B - Positive pole piece and sodium ion battery - Google Patents

Positive pole piece and sodium ion battery Download PDF

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Publication number
CN117457910B
CN117457910B CN202311774652.6A CN202311774652A CN117457910B CN 117457910 B CN117457910 B CN 117457910B CN 202311774652 A CN202311774652 A CN 202311774652A CN 117457910 B CN117457910 B CN 117457910B
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positive electrode
additive
ion battery
electrode active
sodium ion
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CN117457910A (en
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田少杰
臧成杰
郑春龙
刘丽娟
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Tianpeng Lithium Energy Technology Huai'an Co ltd
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Tianpeng Lithium Energy Technology Huai'an Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention provides a positive pole piece and a sodium ion battery, wherein the positive pole piece comprises a current collector and a positive active layer arranged on at least one side surface of the current collector; the positive electrode active layer includes a positive electrode active material, a conductive agent, a binder, and an additive X. According to the invention, the additive X is introduced into the positive electrode plate, so that the processing performance of the positive electrode material and the high-temperature cycle and storage performance of the sodium ion battery can be improved.

Description

Positive pole piece and sodium ion battery
Technical Field
The invention belongs to the technical field of batteries, and relates to a positive plate and a sodium ion battery.
Background
The lithium ion battery is widely applied to the fields of mobile electronic equipment, electric automobiles, unmanned aerial vehicles and the like due to the characteristics of high energy density, long service life, no memory effect and the like. However, lithium has limited reserves on earth, and high cost and low cost can restrict long-term application of lithium batteries. The main element sodium in the sodium ion battery is abundant in the earth, and sodium carbonate which is one of the raw materials is low in price, so that the sodium ion battery is hopeful to be replaced in the near future.
In the field of sodium ion batteries, one positive electrode material with application prospect is a layered oxide material, but the layered oxide is very alkaline, so that the problem of gel in the processing process of positive electrode slurry can be caused, and the decomposition of the positive electrode material and the decomposition and failure of electrolyte components can be aggravated; in addition, the layered oxide is easy to generate phase change under high temperature and high voltage, releases oxygen, can aggravate side reaction of electrolyte and an anode-cathode interface, causes gas production and capacity loss, and finally causes poor processability of the layered oxide anode material and deterioration of high temperature cycle and storage life of the sodium ion battery. Accordingly, there is a need to provide a solution to the above-mentioned problems.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention aims to provide a positive plate and a sodium ion battery. According to the invention, the additive X is introduced into the positive electrode plate, so that the processing performance of the positive electrode material and the high-temperature cycle and storage performance of the sodium ion battery can be improved.
To achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a positive electrode sheet, which includes a current collector and a positive electrode active layer disposed on at least one side surface of the current collector;
the positive electrode active layer comprises a positive electrode active material, a conductive agent, a binder and an additive X, wherein the structural formula of the additive X is shown as formula I:
（Ⅰ），
wherein A is selected from alkyl group with 2-8 carbon atoms or alkenyl group with 2-8 carbon atoms, R 1 、R 2 And R is 3 Independently selected from alkyl groups.
The invention provides a positive electrode plate, wherein an additive X is introduced into a positive electrode active layer, and a cyclic phosphite ester group of the additive X can react with residual alkali in a positive electrode active material to generate a phosphite ester/sodium compound, and the phosphite ester/sodium compound can be used as an interfacial film on the surface of a positive electrode, can block oxidation of electrolyte on the surface of the positive electrode, can consume the residual alkali, and can inhibit the influence of the residual alkali on the processing performance of the positive electrode and the decomposition of the electrolyte in a battery; in addition, the rest of the additive X can be preferentially oxidized at the positive electrode to form a compact interface film in the use process of the sodium ion battery, so that the positive electrode interface is further protected; the P element on the phosphite structure on the additive X contains a lone pair of electrons, can be combined with the metal element in the positive electrode material, and has the function of stabilizing the positive electrode material; the phosphite ester structure on the additive X can also be combined with oxygen release of the positive electrode under high temperature and high voltage to generate phosphate ester/sodium, so that oxidation and gas production of the electrolyte are inhibited; the alkyl silicon group on the additive X can also remove substances such as water, HF, residual alkali and the like in the positive electrode material, and inhibit the corrosion of the substances to the positive electrode material and the decomposition of electrolyte. Therefore, the additive X is introduced into the positive electrode plate, so that the processing performance of the positive electrode material and the high-temperature cycle and storage performance of the sodium ion battery can be improved.
In the present invention, in the alkyl group having 2 to 8 carbon atoms, the carbon atoms may be, for example, 2,3, 4, 5, 6, 7 or 8; in the alkenyl group having 2 to 8 carbon atoms, the number of carbon atoms may be, for example, 2,3, 4, 5, 6, 7 or 8.
Preferably, said R 1 、R 2 And R is 3 Independently selected from alkyl groups having 1 to 3 carbon atoms, which may be, for example, 1,2 or 3.
In the present invention, the term "independently" means R 1 、R 2 And R is 3 The alkyl groups having 1 to 3 carbon atoms may be selected, and the carbon atoms of the alkyl groups may be selected so as not to interfere with each other, independently of each other.
Preferably, the additive X is selected from any one or a combination of at least two of the compounds 1-6:
；/>；/>；
；/>；/>。
the mass content of the additive X is preferably 0.1 to 3% based on 100% of the total weight of the positive electrode active layer, and may be, for example, 0.1%, 0.3%, 0.6%, 0.9%, 1.2%, 1.5%, 1.8%, 2.1%, 2.4%, 2.7%, or 3%, etc., but is not limited to the listed values, and other non-listed values within the range are equally applicable.
In the invention, when the content of the additive X is too high, the interfacial film formed by ring-opening polymerization of the additive X is too thick, thereby preventing the transmission of sodium ions and bringing about the deterioration of cycle and storage performance; when the content of the additive X is too low, the effect of neutralizing residual alkali in the positive electrode and forming a stable and dense interface film on the surface of the positive electrode can not be achieved, and the processability of the positive electrode material and the high-temperature cycle and storage performance of the sodium ion battery can not be improved.
Preferably, the positive electrode active layer further includes an additive Y including a nitrile substance.
In the invention, when the positive electrode active material is a layered oxide, the layered oxide material is easy to decompose at high temperature and high voltage, and part of metal ions are dissolved out of the electrolyte and deposited on the negative electrode, so that the consumption of the electrolyte and active sodium ions on the negative electrode is catalyzed, and the cycle and storage performance of the sodium ion battery are deteriorated. In view of the above, the invention adds the additive Y on the basis of adding the additive X, wherein the additive Y is nitrile substance, the cyano group of the nitrile substance has strong electron withdrawing capability and strong capability of capturing metal ions; the additive Y is coated on the surface of the positive electrode active material, can effectively capture metal ions dissolved out from the positive electrode, inhibit the metal ions from migrating to the electrolyte and the negative electrode to generate side reactions, and can stabilize the surface of the positive electrode, inhibit the oxidation of the electrolyte on the surface of the positive electrode and further improve the performance of the sodium ion battery.
Preferably, the nitrile material comprises any one or a combination of at least two of succinonitrile, adiponitrile, butenedinitrile, xin Erjing, ethyleneglycol bis (propionitrile) ether, 1, 4-dicyano-2-butene, 1,2, 3-tris (2-cyanooxy) propane or 1,3, 6-hexanetrinitrile.
The mass content of the additive Y is preferably 0.1 to 1% based on 100% of the total weight of the positive electrode active layer, and may be, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1%, etc., but is not limited to the listed values, and other values not listed in the range of values are equally applicable.
In the invention, when the content of the additive Y is too high, the additive Y not only complexes metal ions in the positive electrode, but also adsorbs active sodium ions to inhibit migration of the sodium ions on the surface of the positive electrode, thereby deteriorating high-temperature cycle and storage performance. When the content of the additive Y is too low, it is difficult to play a role in effectively capturing metal ions and stabilizing the surface of the positive electrode.
Preferably, the positive electrode active material comprises a layered oxide having a chemical formula of NaM x O y Wherein x is more than or equal to 0.8 and less than or equal to 1.5, y is more than or equal to 1.5 and less than or equal to 2.5, and M is selected from any one or a combination of at least two of Fe, cu, ni, co and Mn.
NaM is used as a material for the electronic device x O y The values of x and y are in charge balance.
In the present invention, x may be, for example, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, or the like. The y may be, for example, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, or 2.5, etc., but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.
Preferably, the positive electrode active material includes NaFe 0.5 Mn 0.5 O 2 、NaNi 0.3 Fe 0.4 Mn 0.3 O 2 、NaNi 0.33 Fe 0.34 Mn 0.33 O 2 、NaNi 0.25 Fe 0.5 Mn 0.25 O 2 、NaNi 0.2 Cu 0.1 Fe 0.4 Mn 0.3 O 2 、NaNi 0.25 Fe 0.4 Co 0.1 Mn 0.25 O 2 、NaNi 0.5 Fe 0.4 Mn 0.4 O 2.4 Or NaNi 0.4 Fe 0.2 Mn 0.3 O 1.8 Any one or a combination of at least two of these.
Preferably, the conductive agent includes any one or a combination of at least two of conductive carbon black, conductive graphite, carbon nanotubes, graphene or carbon fibers.
Preferably, the current collector of the positive electrode sheet is selected from any one of aluminum foil, aluminum foil containing doping elements, or aluminum foil containing a coating layer on the surface.
In a second aspect, the present invention provides a sodium ion battery comprising a positive electrode sheet as described in the first aspect.
Preferably, the sodium ion battery further comprises a negative electrode plate, a separation membrane and electrolyte.
Preferably, the negative electrode material in the negative electrode sheet comprises hard carbon and/or soft carbon.
Preferably, the electrolyte comprises a solvent, an electrolyte salt and an additive.
Preferably, the solvent in the electrolyte solution includes any one or a combination of at least two of carbonate solvent, fluorocarbonate solvent, carboxylate solvent, fluorocarboxylate solvent, ether solvent, or fluoroether solvent.
Preferably, the carbonate solvent comprises any one or a combination of at least two of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl ethyl carbonate or methyl propyl carbonate.
Preferably, the fluorocarbonate solvent comprises any one or a combination of at least two of fluoroethylene carbonate, bis-fluoroethylene carbonate, methyltrifluoromethyl carbonate, methyltrifluoroethyl carbonate or bis (2, 2-trifluoroethyl) carbonate.
Preferably, the carboxylate solvent comprises any one or a combination of at least two of methyl formate, methyl acetate, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, propyl propionate or ethyl butyrate.
Preferably, the fluorocarboxylate solvent comprises any one or a combination of at least two of ethyl fluoroacetate, methyl trifluoroacetate, ethyl trifluoroacetate, propyl trifluoroacetate, 2-trifluoroethyl difluoroacetate, methyl pentafluoropropionate or 2, 2-difluoroethyl acetate.
Preferably, the ether solvent comprises any one or a combination of at least two of tetrahydrofuran, 1, 3-dioxane, diethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether or tetraethylene glycol dimethyl ether.
Preferably, the method comprises the steps of, the fluoroether solvent comprises bis (2, 2-trifluoroethyl) ether 1, 2-tetrafluoroethyl-2, 2-trifluoroethyl ether or 1, 2-tetrafluoroethyl-any one or a combination of at least two of 2, 3-tetrafluoropropyl ether.
Preferably, the electrolyte salt comprises NaPF 6 、NaFSI、NaTFSI、NaBF 4 、NaClO 4 、NaAsF 6 Or NaSbF 6 Any one or a combination of at least two of these.
Preferably, the additive in the electrolyte comprises any one or a combination of at least two of carbonate additives, nitrile additives, sulfur-containing additives, fluorine-containing additives, boron-containing additives, or phosphorus-containing additives.
Further preferably, the additive in the electrolyte comprises any one or a combination of at least two of vinylene carbonate, ethylene carbonate, fluoroethylene carbonate, succinonitrile, adiponitrile, ethylene glycol bis (propionitrile) ether, 1, 4-dicyano-2-butene, 1,2, 3-tris (2-cyanooxy) propane, 1,3, 6-hexanetrinitrile, 1, 3-propane sultone, 1, 3-propenolactone, ethylene sulfite, ethylene sulfate, fluoroethylene sulfate, propylene sulfate, sodium difluorooxalato borate, tris (trimethylsilane) phosphate or tris (trimethylsilane) phosphite.
The numerical ranges recited herein include not only the recited point values, but also any point values between the recited numerical ranges that are not recited, and are limited to, and for the sake of brevity, the invention is not intended to be exhaustive of the specific point values that the recited range includes.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a positive electrode plate, wherein an additive X is introduced into a positive electrode active layer, and a cyclic phosphite ester group of the additive X can react with residual alkali in a positive electrode active material to generate a phosphite ester/sodium compound, and the phosphite ester/sodium compound can be used as an interfacial film on the surface of a positive electrode, can block oxidation of electrolyte on the surface of the positive electrode, can consume the residual alkali, and can inhibit the influence of the residual alkali on the processing performance of the positive electrode and the decomposition of the electrolyte in a battery; in addition, the rest of the additive X can be preferentially oxidized at the positive electrode to form a compact interface film in the use process of the sodium ion battery, so that the positive electrode interface is further protected; the P element on the phosphite structure on the additive X contains a lone pair of electrons, can be combined with the metal element in the positive electrode material, and has the function of stabilizing the positive electrode material; the phosphite ester structure on the additive X can also be combined with oxygen release of the positive electrode under high temperature and high voltage to generate phosphate ester/sodium, so that oxidation and gas production of the electrolyte are inhibited; the alkyl silicon group on the additive X can also remove substances such as water, HF, residual alkali and the like in the positive electrode material, and inhibit the corrosion of the substances to the positive electrode material and the decomposition of electrolyte. Therefore, the additive X is introduced into the positive electrode plate, so that the processing performance of the positive electrode material and the high-temperature cycle and storage performance of the sodium ion battery can be improved.
Detailed Description
The technical scheme of the invention is further described by the following specific embodiments.
The additives used in the following examples and comparative examples are specifically as follows:
the additive X is any one of the compounds 4 to 6:
；/>；/>；
the additive Y is adiponitrile or 1,3, 6-hexanetrinitrile.
Example 1
The embodiment provides a positive electrode plate, which comprises a current collector and positive electrode active layers arranged on the surfaces of two sides of the current collector;
the positive electrode active layer comprises a positive electrode active material, a conductive agent, a binder and an additive X, wherein the positive electrode active material is sodium nickel iron manganese oxide NaNi 0.3 Fe 0.4 Mn 0.3 O 2 The adhesive is polyvinylidene fluoride, the conductive agent is conductive carbon black, and the additive X isThe mass ratio of the compound 5, the sodium ferronickel manganate, the polyvinylidene fluoride and the conductive carbon black is 96:2:2; the total mass content of the sodium ferronickel manganate, polyvinylidene fluoride and conductive carbon black was 99.9% and the mass content of the additive X was 0.1% based on 100% of the total mass of the positive electrode active layer.
The embodiment also provides a preparation method of the positive plate, which comprises the following steps:
mixing an anode active material, a conductive agent, a binder and an additive X, adding N-methyl pyrrolidone (NMP), and stirring to prepare anode slurry, wherein the mass fraction of NMP in the anode slurry is 28%; uniformly coating the anode slurry on an aluminum foil, wherein the coating surface density is 30mg/cm 2 And (3) airing the coated aluminum foil at room temperature, transferring to a 110 ℃ oven for drying for 1h, then carrying out cold pressing, trimming, cutting and slitting, drying for 4h under a vacuum condition at 100 ℃, and welding the tab to obtain the positive electrode plate.
Examples 2-13 and comparative example 1 were modified on the basis of example 1, the parameters of the specific modification are shown in Table 1, and the remaining preparation methods and parameters remain the same as in example 1.
TABLE 1
Performance testing
1. Positive electrode slurry viscosity test
At 25 ℃, a part of the positive electrode slurry prepared in the above examples and comparative examples was taken and left to stand for 24 hours, and then the viscosity of the slurry was tested and recorded.
2. Sodium ion battery performance test
Assembling the positive electrode plate, the negative electrode plate, the diaphragm and the electrolyte obtained in the embodiment and the comparative example into a sodium ion battery;
the preparation method of the electrolyte comprises the following steps: in a glove box, firstly slowly adding sodium hexafluorophosphate into a mixed solvent of Ethylene Carbonate (EC), dimethyl carbonate (DMC) and methyl ethyl carbonate (EMC), and adding 1% fluoroethylene carbonate (FEC) additive after the temperature in a container is reduced to room temperature; wherein the mass ratio of EC, DMC and EMC is 1:1:1, and the mass fraction of sodium hexafluorophosphate in the electrolyte is 14%;
the preparation method of the negative electrode plate comprises the following steps: dissolving hard carbon, sodium carboxymethylcellulose (CMC), styrene-butadiene rubber emulsion (SBR) and conductive carbon black in deionized water according to a mass ratio of 94:1:2:3, and uniformly mixing to prepare negative electrode slurry, wherein the mass fraction of deionized water in the negative electrode slurry is 46%; uniformly coating the cathode slurry on copper foil, wherein the coating surface density is 14mg/cm 2 Drying at 90 ℃ and then carrying out cold pressing, trimming, cutting and slitting, drying for 4 hours at 100 ℃ under vacuum, and welding the tab to prepare a negative electrode plate;
the diaphragm is a Polyethylene (PE) diaphragm, and 3 mu m ceramic coatings are arranged on two sides of the PE diaphragm. A commercial manufacturer of the diaphragm is Shanghai Enjie, and the model is SV16. The preparation process of the diaphragm comprises the following steps: and dissolving the boehmite ceramic material in deionized water to form slurry, coating boehmite layers on the two sides of the polyvinyl film in a gravure coating mode, and drying to obtain the diaphragm.
And winding the positive electrode plate, the negative electrode plate and the diaphragm into a bare cell, then filling the bare cell into an aluminum plastic film, baking at 90 ℃ for water removal, injecting electrolyte, sealing, standing, hot-cold pressing, forming, exhausting, separating the volume and the like, and thus obtaining the sodium ion battery.
(1) 45 ℃ high temperature cycle performance test
The sodium ion battery is kept stand for 30 minutes at 45 ℃, then is charged to 4.05V at constant current with 0.5C multiplying power, then is charged to 0.05C at constant voltage with 4.05V, and is kept stand for 5 minutes, then is discharged to 2.0V at constant current with 0.5C multiplying power, and the discharge capacity is the first discharge capacity C of the sodium ion battery after a charge-discharge cycle process 1 The method comprises the steps of carrying out a first treatment on the surface of the Then 400 charge-discharge cycles are carried out, and the discharge capacity of the 400 th cycle is recorded as C 400 The method comprises the steps of carrying out a first treatment on the surface of the Capacity retention after 400 cycles of sodium ion cell = C 400 /C 1 。
After all the sodium ion battery tests are completed, disassembling the battery cells, taking out the negative electrode plate, scraping the negative electrode active layer, digesting with strong acid, filtering to prepare a solution, testing the content of iron, nickel and manganese in the obtained solution by ICP (inductively coupled plasma), and recording, wherein the sum of the content of iron, nickel and manganese obtained by ICP test is the sum of the deposition amount of negative electrode metal ions.
(2) High temperature storage test at 60 DEG C
Firstly, standing a sodium ion battery at 25 ℃ for 30 minutes; charging to 4.05V at a constant current of 0.5C, further charging to a current of 0.05C at a constant voltage of 4.05V; the volume of the cell, here the volume before storage V, was measured by drainage 0 The method comprises the steps of carrying out a first treatment on the surface of the Then the sodium ion battery is stored for 60 days at 60 ℃, after the storage is finished, the volume of the battery is tested by adopting a drainage method, wherein the volume is V after the storage 60 。
Volume expansion rate= (V) of sodium ion battery after 60 days of storage 60 -V 0 )/V 0 。
The test data are detailed in table 2.
TABLE 2
Analysis:
in Table 2, it can be seen from the results of examples 1 to 3, examples 5 to 6 and comparative example 1 that the effect of adding the additive X to the positive electrode sheet is better than that of the positive electrode sheet without the additive X, wherein the additive X can consume residual alkali in the positive electrode, and the viscosity and the gel phenomenon after 24 hours of standing are obviously improved, so that the processing performance of the positive electrode sheet is improved; the additive X can also inhibit side reaction in forming a compact interface film, phosphite ester groups on the additive X can be combined with oxygen release, silane groups on the additive X can remove polar small molecules such as water, HF, residual alkali and the like, so that the high-temperature cycle and storage performance of various sodium ion batteries are obviously improved.
From the results of examples 1 to 4 and example 7, it can be seen that the viscosity, 45 ℃ cycle capacity retention rate and negative electrode metal ion deposition, 60 ℃ storage volume expansion rate of the positive electrode slurry were all gradually improved after 24 hours of standing as the addition amount of the additive X in the positive electrode sheet of the sodium ion battery was increased. However, when the additive X is excessively used, the interfacial film formed by ring-opening polymerization of the additive X is excessively thick, thereby blocking the transmission of sodium ions, which may cause deterioration of cycle and storage properties. When the additive X is too small, the effects of neutralizing residual alkali of the positive electrode and forming a film on the surface of the positive electrode are difficult to achieve, and the processing performance of the positive electrode material and the high-temperature cycle and storage performance of the sodium ion battery cannot be improved.
From the results of examples 5, 8-10 and 12, it can be seen that, on the basis of adding the additive X into the positive electrode sheet, the additive Y is added, so that the circulation capacity retention rate at 45 ℃ and the storage volume expansion rate at 60 ℃ are improved to some extent, and especially the deposition improvement of the negative electrode metal ions is obvious, because the complexing ability of the additive Y to the metal ions is strong, and the damage effect of dissolved metal ions to the electrolyte and the negative electrode is inhibited.
From the results of examples 8 to 11 and example 13, it can be seen that the viscosity of the positive electrode slurry, the circulation capacity retention rate at 45 ℃ and the deposition of negative electrode metal ions and the storage volume expansion rate at 60 ℃ gradually improve after 24 hours, on the basis of adding the additive X to the positive electrode sheet, as the content of the additive Y increases, but when the additive Y is excessive, the additive Y not only complexes the metal ions in the positive electrode but also adsorbs active sodium ions, blocking migration of the sodium ions on the surface of the positive electrode, thereby deteriorating the performance of the sodium ion battery. When the additive Y is too small, it is difficult to effectively capture metal ions and stabilize the positive electrode, and the effect of improving the performance is limited.
In summary, the additive X is used in the positive electrode plate of the sodium ion battery, so that the processing performance of the positive electrode plate can be obviously improved, and the high-temperature cycle and the high-temperature storage life of the sodium ion battery can be prolonged; on the basis of using the additive X in combination in the positive electrode plate, the additive Y is added, so that the deposition of metal ions on the negative electrode can be inhibited, and the high-temperature cycle and storage performance of the sodium ion battery are further improved.
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and it should be apparent to those skilled in the art that any changes or substitutions that fall within the technical scope of the present invention disclosed herein are within the scope of the present invention.

Claims (10)

1. The positive electrode plate is characterized by comprising a current collector and a positive electrode active layer arranged on at least one side surface of the current collector;
the positive electrode active layer comprises a positive electrode active material, a conductive agent, a binder and an additive X, wherein the structural formula of the additive X is shown as formula I:
（Ⅰ），
wherein A is selected from alkyl group with 2-8 carbon atoms or alkenyl group with 2-8 carbon atoms, R 1 、R 2 And R is 3 Independently selected from alkyl groups;
the positive electrode active material includes a layered oxide.
2. The positive electrode sheet according to claim 1, wherein R 1 、R 2 And R is 3 Independently selected from alkyl groups having 1 to 3 carbon atoms.
3. The positive electrode sheet according to claim 1, wherein the additive X is selected from any one of compounds 1 to 6 or a combination of at least two of them:
；/>；/>；
；/>；/>。
4. the positive electrode sheet according to claim 1, wherein the mass content of the additive X is 0.1 to 3% based on 100% of the total weight of the positive electrode active layer.
5. The positive electrode sheet according to claim 1, wherein the positive electrode active layer further comprises an additive Y, the additive Y comprising a nitrile substance.
6. The positive electrode sheet according to claim 5, wherein the nitrile substance comprises any one or a combination of at least two of succinonitrile, adiponitrile, butenedinitrile, xin Erjing, ethyleneglycol bis (propionitrile) ether, 1, 4-dicyano-2-butene, 1,2, 3-tris (2-cyanooxy) propane, or 1,3, 6-hexanetrinitrile.
7. The positive electrode sheet according to claim 5, wherein the mass content of the additive Y is 0.1 to 1% based on 100% of the total weight of the positive electrode active layer.
8. The positive electrode sheet according to claim 1, wherein the layered oxide has a chemical formula of NaM x O y Wherein x is more than or equal to 0.8 and less than or equal to 1.5, y is more than or equal to 1.5 and less than or equal to 2.5, and M is selected from any one or a combination of at least two of Fe, cu, ni, co and Mn.
9. A sodium ion battery comprising the positive electrode sheet of any one of claims 1-8.
10. The sodium ion battery of claim 9, further comprising a negative electrode tab, a separator, and an electrolyte;
the negative electrode material in the negative electrode plate comprises hard carbon and/or soft carbon;
the electrolyte comprises a solvent, electrolyte salt and an additive;
the additive in the electrolyte comprises any one or a combination of at least two of a carbonate additive, a nitrile additive, a sulfur-containing additive, a fluorine-containing additive, a boron-containing additive or a phosphorus-containing additive.
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